This invention relates generally to palletizers and more particularly to means for forming configurable patterns of product during the palletizing process.
Conveyor systems and palletizers are constructed to quickly move products from an upstream location to a palletizer section in which the product is arranged and stacked in layers for packaging and transport. There are various patterns of stacking that improve the stability of the load on the pallet. For instance, when stacking rectangular cases of consumer goods or bags of various material, the first layer of cases are arranged lengthwise along the back of the pallet and a row of cases are arranged sideways along the front of the pallet. In the next layer, the arrangement is reversed so that the back of the pallet has cases arranged sideways and the front has cases arranged lengthwise. This pattern of alternating layers is repeated until the pallet is fully loaded and the load wrapped for transport.
Pattern formation requires that the cases be properly positioned at the appropriate x-y location on the layer and in the needed orientation. This pattern formation is complicated by the fact that there may be many such patterns required for various goods and that variations in case sizes may require customized configuration of the palletizing equipment. That is, while conveyors are typically linear and have a single lane along which goods pass, cases within a palletized layer would have to be laterally positioned differently from adjacent cases. This may require lateral movement of the downstream end of the single-lane conveyor or, alternately, movement of the case to a fixed lateral lane along a multilayer conveyor. Such cases, however, would still need to be turned in order to properly orient the cases within the pallet layer.
Stacking with alternate rows improves the stability of the pallet because seams are overlaid and the cases contact multiple cases on adjacent layers. This in contrast with stacking using the same pattern where each case is in a single uniform column of such cases that are not stabilized by overlapping and thus stand a greater chance of collapsing.
One problem with stacking with alternating layers is that the orientation of the cases must be necessarily turned so that the product can be placed in either lengthwise or sideways fashion on the pallet. While such turning had been done manually, more modern equipment turn product using automated turners such as U.S. Pat. No. 6,032,782, owned in common by the assignee of the present invention. The turners operate by driving the product against a turning surface that is off axis to the direction of movement of the product along the conveyor. This causes the product to pivot around the turning surface so that it rotates ninety degrees. Such turners are typically static, however, and are fixed within a particular conveyor lane. As a result, there must be a different turner for each lane of a conveyor and pattern formation is limited to a particular preset pattern rather than dynamic as might be required when stacking products of different sizes or configurations.
A need arises, therefore, for a more flexible approach so that product turning can be dynamically controlled and multiple patterns formed using only a limited number of turning devices.